The invention was not made by an agency of the United States Government nor under contract with an agency of the United States Government.
This invention relates generally to devices and methods used in the precision assembly of component parts, and specifically to devices and methods for terminating optical cables by connecting optical fibers to optical connectors.
Numerous manufacturing processes involving the assembly of component parts require that a first component part be accurately placed within or inserted into a second component. Often these components are extremely small or fragile, and assembly requires devices and methods which are specifically designed to accommodate such components. Satisfactory assembly of these components also depends upon accurate alignment of the components relative to one another such that a precise fit between certain parts is achieved. Furthermore, accurate alignment of a first component and a second component which is to receive and form a union with the first component is also necessary to prevent jamming, fracturing, or breaking of one or both of the components. However, such precise alignment is often difficult and prohibitively expensive to attain because additional steps must be added to existing processes, or special devices must be designed and implemented to achieve acceptable results. Therefore, there is a need for devices and methods that promote precise alignment between components which can be quickly and inexpensively incorporated into existing manufacturing systems. The use of vibratory or wave energy to increase the accuracy and efficiency of existing systems achieves such a result.
Vibratory or wave energy at varying frequencies, amplitudes and power densities can be utilized at different phases of the manufacturing process. Firstly, vibratory or wave energy can be used for mixing two or more adhesive compounds without generating unwanted heat which may cause an adhesive mixture to cure prematurely. Furthermore, a mixing process utilizing vibratory or wave energy can effectively degas the mixed components if the mixed components are liquids. Secondly, vibratory or wave energy facilitates the flow of certain viscous liquids, such as adhesives, into small spaces where wetting of all surfaces is desired, and complete filling of the small space, without voids or gaps is necessary. Thirdly, vibratory or wave energy may be used to promote joining or alignment of close tolerance parts, particularly when these parts are small in size and fragile in nature. The application of vibratory or wave energy tends to naturally center a first part relative to a second part, when the first part must be inserted through an opening in the second part. This effect results from the tendency for a component, part, or other object to seek its lowest energy state. This tendency is a critical element in automating the assembly of fiber optic components, and may be equally useful in the assembly of close tolerance machinery, various electronic components, and other items of manufacture. Fourthly, vibratory or wave energy can be used to heat materials, and may be utilized in heat bonding or heat curing certain materials. Adhesives which normally take minutes or even hours to cure, can be heat-cured in just seconds with the application of vibratory or wave energy. Thus, vibratory or wave energy curing processes can greatly reduce the time required to assemble certain parts.
There are a variety of known uses for vibratory and wave energy in industrial processes. U.S. Pat. No. 4,176,909 to Prunier discloses a process for fixing a connector to a fiber optic cable by ultrasonically welding a connector made of a thermoplastic material to an optical cable while exerting radial compressive force on the assembly. U.S. Pat. No. 4,265,689 to Jeffrey discloses a method of joining glass objects utilizing ultrasonics. U.S. Pat. No. 4,339,247 to Faulkner et al. discloses a method of separating a dissolved gas from a liquid by means of an acoustic transducer. U.S. Pat. No. 4,548,771 to Senapati et al. provides a method for vulcanizing rubber by mean of applying ultrasonic energy. U.S. Pat. No. 4,867,817 to Kneafsey et al. provides a method for activating microencapsulated chemical compositions by sonication. U.S. Pat. No. 5,300,162 to Brockmeyer et al. discloses a process for producing an optical coupler by ultrasonically welding polymeric optical fibers to a plastic tube; and U.S. Pat. No. 5,690,766 to Zwick discloses a method of bonding an integrated circuit chip to a lead frame which includes the step of applying vibrations from an acoustic source to temporarily change adhesive rheology during the manufacturing process. However, the prior art does not address the use of vibratory energy to facilitate precision assembly of components or parts in an industrial process such as the assembly of fiber optic connectors.
Fiber optic technology plays a crucial role in modern communications. However, for fiber optic cables to be useful, optical fibers must be precisely aligned so that the signal from one cable passes to another cable with minimal loss of the signal. The fiber optics industry has developed a number of standard connectors that can be affixed to the ends of optical fibers for precisely positioning the ends of two optical fibers relative to one another. Attaching an optical connector to the end of a fiber optic cable is referred to as a termination. These terminations are produced in large quantities, and due to the extremely close tolerances between the fiber and the connector required for high transmission rates at the connection between fibers, such terminations must conform to exacting requirements to function properly. Optic fiber terminations are typically assembled by trained laborers who perform most or all of the steps manually. The assembly process requires much skill, and due to frequent technician error, the quality of terminations produced is not consistent. Therefore, devices and methods are needed which can effectively automate the assembly process thereby consistently producing high quality optical fiber terminations.
There are four primary aspects to the process for assembling fiber optic terminations: (a) preparing the adhesive or epoxy which is injected into the optical connector, (b) injecting the correct volume of adhesive into the optical connector, (c) accurately inserting the optical fiber into the optical connector, and (d) curing the adhesive within the optical connector following insertion of the optical fiber into the connector. Preparation and curing of the adhesive can be accomplished by utilizing vibratory or wave energy, as previously described. However, additional methods and devices are needed to accomplish the adhesive injection and fiber insertion steps.
As previously stated, the adhesive injection step is currently accomplished manually through the efforts of a skilled technician. Despite skill and training, these efforts still require guesswork, and can produce unacceptable numbers of nonfunctional terminations. Thus, there is a need for an automated adhesive injection system that consistently dispenses the correct amount of adhesive into an optical connector. Several methods are known regarding injection of adhesive into optical connectors. U.S. Pat. No. 5,815,619 to Bloom discloses a fiber optic connector which is hermetically terminated. U.S. Pat. No. 5,858,161 to Nakajima et al. provides a method for assembling a fiber optic connector which includes the use of a specially designed jig for injecting epoxy into a connector, and U.S. Pat. No. 5,913,001 to Nakajima et al. discloses a similar epoxy injection device. However, these methods and devices do not address the issue of automation of the injection process so to minimize technician inconsistency and error.
As with the adhesive injection step, insertion of an optical fiber into an optical connector is also accomplished manually. This manual process is time-consuming and the results are inconsistent and unpredictable; therefore, there is a need for an automated system that can mass produce functional optical fiber terminations quickly and consistently. Currently, there are a variety of known methods and devices for inserting optical fibers into optical connectors to form a termination. See, for example, U.S. Pat. No. 4,666,237 to Mallison, U.S. Pat. No. 4,673,245 to Kling et al., U.S. Pat. No. 4,681,398 to Bailey et al., and U.S. Pat. No. 5,058,984 to Bulman et al. U.S. Pat. No. 5,113,474 to Slaney et al. discloses a hand-held device for assembling fiber optic connectors by application of a selected force which does not break the optical fiber. U.S. Pat. No. 5,235,664 to Okada et al. provides an apparatus for making an optical fiber termination which utilizes a guiding aperture to center the fiber relative to the connector. U.S. Pat. No. 5,261,020 to de Jong et al. provides an optical fiber connector assembly tool which utilizes a crimp tube disposed around the cable to be terminated, and U.S. Pat. No. 5,442,724 to Deuel discloses a hand tool for terminating a fiber optic cable to a connector by crimping the connector itself. U.S. Pat. No. 5,917,975 to Bloom discloses an apparatus for forming a low-stress fit of an optical fiber to a connector by means of heat expansion of the ferrule of a connector. However, the prior art does not provide an integrated, automated system that provides feedback data to the user to ensure high-volume, highly accurate assembly of optical fiber terminations.
Accordingly, these and other disadvantages of the prior art are overcome by this invention which provides an integrated, automated, highly accurate system for terminating optical cables. While this system includes both methods and devices for assembling optical fibers and optical connectors, it is important to note that certain aspects of the present invention, namely the various applications of vibratory or wave energy, are applicable to manufacturing and precision assembly in general, and are in no way limited to fiber optic methods and devices.
The present invention provides a system which encompasses the entire process of terminating an optical fiber with an optical connector, and which utilizes data from feedback modules to ensure accuracy and consistency. This invention provides an apparatus and method for preparing adhesive for injection into an optical connector; an apparatus and method for injecting the adhesive into the optical connector; an apparatus and method for inserting a fiber optic cable into the optical connector; and a method for curing the adhesive following insertion of optical fiber into said optical connector.
The system for preparing adhesive for injection into the optical connector includes a device in communication with the adhesive which generates vibratory or wave energy at frequencies and intensities sufficient to mix and de-gas the adhesive, as well as an automated system for mixing and degassing at least two materials. The apparatus for injecting adhesive into an optical connector includes a receptacle for holding the adhesive, and a means for dispensing the adhesive into an optical connector. The apparatus for inserting a fiber optic cable into an optical connector includes a base assembly; a means attached to the base assembly for holding an optical fiber, an optical connector holder positioned opposite the optical fiber, a means for orienting the base assembly and the optical connector holder relative to one another, and a feedback module for centering the optical fiber relative to the optical connector. The optical fiber insertion apparatus includes a device in communication with certain parts of the apparatus for generating vibratory or wave energy at frequencies and intensities which promote the centering of the optical fiber in the optical connector, and which facilitate the assembly of the fiber and connector. The process for curing the adhesive following the insertion of optical fiber into the optical connector includes a device in communication with the optical connector for generating vibratory or wave energy at frequencies and intensities sufficient to heat and cure the adhesive in the optical connector before the terminated optical cable is removed from the assembly apparatus.
Therefore, it is an object of the present invention to provide methods and devices that utilize vibratory or wave energy to facilitate the precision assembly of close tolerance components or parts.
It is a further object of the present invention to provide a manufacturing or assembly process that utilizes vibratory or wave energy to cure adhesive materials.
Another object of the present invention is to provide a manufacturing or assembly process that utilizes vibratory or wave energy to mix and degas materials.
Another object of the present invention is to provide methods and devices for promoting the flow of adhesives into narrow or small regions of components, promoting the wetting of surfaces, and improving the resulting adhesive bond between the components.
Still another object of the present invention to provide an integrated, automated, high-throughput system for terminating fiber optic cables.
Still another object of the present invention is to provide an intelligent system that supplies the user with feedback data to assure a highly accurate and consistent assembly process.
Further objects, advantages, and novel aspects of this invention will become apparent from a consideration of the drawings and subsequent detailed description.
Optical Cable
10 Fiber Optic Cable
12 Outer Jacket
14 Buffer
16 Optical Fiber
Optical Connector
20 Optical Connector
22 Outer Shell
24 Spring-Loaded Base
26 Ferrule
28 Ferrule Bore
30 Plenum
Mixing and Degassinci Apparatus
40 Mixing and Degassing Apparatus
41 First Tank
42 Second Tank
43 First Pump and Metering Device
44 Second Pump and Metering Device
45 Energy Source
46 Horn
47 Mixing Chamber
48 Vent
49 Third Pump and Metering Device
Adhesive Injection Apparatus
50 Adhesive Injection Apparatus
52 Mounting Bracket
54 Housing
56 Vertical Support Panel
58 Upper Horizontal Panel
60 Lower Horizontal Panel
62 Notch
64 Alignment Rods
66 Clamp
68 Syringe
70 Barrel
72 Needle
74 Plunger
76 Plunger Block
78 Load Cell
80 Motor
82 Control Module
84 Holding Block
86 Cavity
88 Apertures
90 Energy Source
92 Horn
Assembly Apparatus
100 Assembly Apparatus
102 Command Module
104 Motor
106 Positioning Table
108 Lead Screw
110 Base Assembly
112 Traveling Block
114 First Positioning Block
116 Base Plate
118 First Pair of Clamping Arms
120 Second Pair of Clamping Arms
122 First V-Shaped Groove
124 Second V-Shaped Groove
126 Clamping Magnets
128 Hinge Pins
130 Center Alignment Stop
132 Opener Rod
134 Feedback Module
136 Force Transducer
138 Sensor Assembly
140 Optical Connector Holder
142 Vertical Support
144 Mounting Bracket
146 Second Positioning Block
148 Data Processing Unit
150 Energy Source
152 Horn